IGlossary
B-32 Centillion 1200N ATM Switch User Manual
NTP 297-8103-903
HBFG
Host Behavior Functional Group: The group of functions performed by an ATM-
attached host that is participating in the MPOA service.
HDLC
High Level Data Link Control: An ITU-TSS link layer protocol standard for point-
to-point and multi-point communications.
Header
Protocol control information located at the beginning of a protocol data unit.
HEC
Header Error Control: Using the fifth octet in the ATM cell header, ATM equipment
may check for an error and corrects the contents of the header. The check character
is calculated using a CRC algorithm allowing a single bit error in the header to be
corrected or multiple errors to be detected.
Hello Packet
A type of PNNI Routing packet that is exchanged between neighboring logical
nodes.
Hierarchically Complete Source Route
A stack of DTLs representing a route across a PNNI routing domain such that a
DTL is included for each hierarchical level between and including t he current le vel
and the lowest visible level in which the source and destination are reachable.
Hop-by-Hop Route
A route that is created by having each switch along the path use its own routing
knowledge to determine the next hop of the route, with the expectation that all
switches will choose consistent hops such that the call will reach the desired
destination. PNNI does not use hop-by-hop routing.
Horizontal Link
A link between two logical nodes that belong to the same peer group.
I
IASG
Internetwork Address Sub-Group: A range of internetwork layer addresses
summarized in an internetwork layer routin g protocol.